Radio alarm signal system



R. M. KEATOR RADIO ALARM SIGNAL SYSTEM Aug. 7, 1928.

Filed July 2, 1921 Patented Aug; 7, 1928.

RANDALL M. KEATOIR OF NEW YORK, N. Y., ASSIGNOR JPPIONE 85'1ELEGRAPI-ICOMPANY, OF NEW YORK, N. Y., A CORPORATION OF DELA- WARE.

TO DE FOREST RADIO TELE- RADIO ALARM SIGNAL SYSTEM.

Application filed July 2, 1921. Serial No. 482,024..

' This invention relates to the application of utilizing radio waves fortransmitting alarm signals such as "firefalarm signals,

police call signals, etc. y p

The object of the invention is toprovide an instrumentality whichwi1l'permitutili-' zation of radio signals for the purposes specified,which is simple in structure, highly efficient in operation andeconomical of manufacture, installation and maintenance. A furtherobject of the invention is to provide a self-contained transmittingstation for radio transmission of signals.

'ldu'rtherobjects of the invention will appear more fully hereinafter. g

The invention consistssubstantially in the 7 construction, combination,location and relative arrangement of parts, all as will be more fullyhereinafter set forth, as shown in the accompanying drawing, and finallypointed out in the appended claims.

Referring to the drawing:

Figure 1 is a diagrammatic view showing a transmitting system embodyingmy invention.

Fig. 2 is a view, in elevation, partly in section, showing the sameapplied to its support, and the antenna employed in connectiontherewith.

Fig. 3 is a fragmentary View of a modified construction of the antennaemployed in my invention.

The same part is designated by the same reference character wherever itoccurs throughout the several views.

It is among the special purposes of my present invention to provide atransmitting station which is a self-contained unit including thetransmitter apparatus, the antenna and the ground connection. It will beapparent that with such a transmitter unit,

among the numerous applications that could and scope of my invention asdefined in the claims.

In Fig. 1, however, I have shown the usual housing 1, preferably of thefire or police alarm call box mechanism, including the pull lever 2, thetrain of gears 3 pro polled by the release of the pull lever 52 actingunder the impulse of the spring 4. The train of gears 3 controls theoperation of a signal or key disc 5 provided with teeth 6 spaced apartfrom each other and of the required circumferential length to simulatethe dot and dash code or signal. Uponrotation of the key or signal disc5 a switch 15 is actuated to close a normally open circuit including asource of current 7 and primary coil 8 of a spark coil. The secondarycoil 9 of the spark coil is connected at its terminals across acondenser 10. In shunt across the condenser 10 is the spark dischargecircuit con sisting of a few turns of a helix 11 and the spark gap 12;an antenna lead 13 is also connected to the helix 11. The position onthe helix of contact 14 of the spark discharge circuit, taken inconnection with the capacity of the condenser 10, determines the wavelength radiated by the system. A radiating antenna 16 consists of aclosely wound coil extending preferably above the call box 1 and woundaround a di-electric core which may be the wooden supporting pole 17,which may be either solid or hollow or may be in the form of lattice orframe construction, as shown in Fig. 3, and the antenna wire 18 ispreferably of insulated wire.

It is essential that the coiled antenna wire 18 extend all the waydownward from the of any desired top of the pole 17, but the coiledportion 7 thereof may be limited to a few feet of the pole, and astraight vertical conductor lead ing down from the bottom of the coiledportion to the helix 11 within the housing 1, may be employed. I havefound it, however, to be-esscntial that the coiled antenna earth system,the earth connection being made from the end of the helix 11 within thecasing, shall have a strongly marked resonance period of vibration, i.e., must be a good oscillator due to its large distributed inductanceand relatively small capacity. I have also found it to be essential thatthe suchxan arrangement wherein the base sup- 1 port 19 is of metal,preferably hollow, which supports the box 1 and in which the antennasupport 17 which, in this instance, is a round pole or post of wood offibre, set down into a socket formed by the hollow top. of the ironpedestal. If the antenna frame be made of the open frame or latticeconstruction the same maybe fastened at its base to the top of the ironpost 17 as shown in Fig.3. Y

Many other modifications and changes in detail of construction willreadily occur to those skilled in the art and I, therefore, do

not desire to be limited or restricted in these respects l K e i I makeno claimto the particular instrumentalities employedfor closing thesignal circuit comprising the switch 15, battery source 7 and the coilS,as any of the standard arrangements employed at the present time may beutilized for this purpose; but

having now set forth the objects and nature of my invention, and havingshown and described a construction embodying the principles thereof whatI claim'as'new and useful and of my own invention, and desire to secureby Letters Patent, is: V V

1. The combination with radio transmitting apparatus of a casingtherefor, of a metal post for supporting said casing and provided with anon-conducting portion extending above said casing, and a resonantantenna coilin a helix wound around the nonconducting portion "of saidpost and connect-- ,ed to said apparatus.

'2. The cornb'natien w th radio transmit ting apparatus, of acasingtherefor, of a metal post forsupporting saidf'casing and providedwith a non-conducting portion extending above said casing, a resonant antenna coil in a helix wound around. the non-conductinglporti'on of saidpost and connected to said apparatus, and a ground connection betweensaid apparatus and said metal post. v I

In testimony whereof I have hereunto set my hand on this 30th day ofJune, A.'D.

- RANDALL, KEATOR;

